In the chemical industry, a catalyst plays a critical role for enhancing reaction activity, reducing reaction time and reducing production cost. In general, catalysts may be classified into homogeneous catalysts and heterogeneous catalysts. Homogeneous catalysts usually have high activity and selectivity, but are not easy to be recycled, resulting in high production cost. Heterogeneous catalysts are easy to be recycled, but have lower conversion rate, poor selectivity, and need stricter reaction conditions in comparison with homogeneous catalysts.
Heterogeneous catalysts can be used in C—C coupling reactions. U.S. Pat. No. 6,603,013 discloses a C—C coupling reaction of α-bromostyrene and phenylboronic acid using a heterogeneous palladium catalyst deposited on a carbon black. This kind of heterogeneous catalyst can be easily separated out from the product, but has slower reaction rate, and may have problems of having metal ion leaching out from the carbon black. US Patent Application Publication No. 2008/177,112A discloses a palladium nano particle for catalyzing a C—C coupling reaction. However, this nano particle has slower reaction rate, thus the reaction needs to be performed at higher temperature and pressure and takes longer time to obtain a desired conversion rate.
In addition, in the chemical industry, homogeneous catalysts are also widely used. For example, CN1,686,972 discloses an organic palladium (Pd) catalyst for catalyzing a C—C coupling reaction to produce a liquid crystal compound used for TFT-LCD. The requirement of high purity liquid crystal compound demanded a costly purification process. In addition the homogeneous catalyst used cannot be recovered, resulting in high production cost.
Hence, there is still a need from the industries to develop a catalyst, which has high reactivity and being easy to be recovered.